SEOUL - A South Korean victim of sex slavery for the Japanese Imperial Army during World War II died on Sunday, reducing the number of living victims to six, an advocacy group for the victims said Monday.

Lee Ok-seon passed away on Sunday night at the age of 97, the House of Sharing said on its website.

With her death, only six "comfort women" victims are alive here. "Comfort women" refer to girls and women duped, abducted or forced into sex enslavement for Imperial Japan's military brothels before and during World War II.

READ MORE: WWII: ROK court orders Japan to compensate sex slavery victims

According to historians, at least 200,000 women were deceivably or forcibly sent to the so-called "comfort stations" of the Japanese Imperial Army in Japan, China, Southeast Asia and islands of the South Pacific.

A total of 240 South Korean women have identified themselves as victims of wartime sex slavery.

The sex slavery victims and civic group activists have held rallies every Wednesday in front of the Japanese embassy in Seoul since Jan 8, 1992, calling for an apology and reparation from the Japanese government.

READ MORE: Philippine women group slams Japan's lack of remorse for WWII cruelties

The Korean Peninsula was colonized by Japan from 1910 to 1945.